Rates of chronic diseases vary substantially among American Indian and Alaska Natives (AIAN) communities and tribes for reasons that are largely unknown. Trends in chronic disease incidence and mortality are not well-documented for most tribes, but it does seem clear that diabetes and heart disease incidence and mortality have been increasing over the past two decades and that there is a fivefold variation in incidence rates of cancer among AIAN. While some of the variation in disease rates may have a genetic basis, most likely variations in dietary intake, physical activity patterns, and other lifestyle characteristics contribute to these differences. Few studies of the etiology of chronic diseases have been done in AIAN. Particularly lacking are cohort studies. While numerous cohorts have been established in the last 25 years, the AIAN populations remain the single ethnic population in the United States that has not been included in either the ongoing National Nutrition Monitoring System or large cohort studies. The major scientific goal of the American Indian Alaska Native cohort study, (referred to as EARTH or Education And Research Towards Health) is to determine how diet, physical activity, and other lifestyle and cultural factors relate to the development and progression of chronic diseases such as cancer, cardiovascular diseases, stroke, diabetes, chronic lung and respiratory diseases, and age at time of death. We will examine why some people remain healthy when others develop these diseases. To date, this is the largest and most comprehensive study of diet and lifestyle influences on disease among American Indians and Alaska Natives. In order to understand the nature of the relationship of physical activity to health and disease a valid and reliable measure of physical activity is necessary. Validation of the physical activity questionnaire for this population is the main objective of this proposal. The availability of a valid instrument could potentially enhance future lifestyle surveillance efforts.